Associative array/Creation: Difference between revisions
→{{header|Ruby}}: add examples of literals; format code with spaces as conventional
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=={{header|Ruby}}==
===Hash literals===
A hash object that returns [[nil]] for unknown keys▼
Ruby has literal syntax for Hash objects.
<syntaxhighlight lang="ruby">hash={}▼
hash[666]='devil'▼
A Hash with symbols as keys:
<syntaxhighlight lang="ruby">
{:name => 'Zeus', :planet => 'Jupiter'}
</syntaxhighlight>
Shorthand for symbol keys:
<syntaxhighlight lang="ruby">
{name: 'Zeus', planet: 'Jupiter'}
</syntaxhighlight>
A Hash with keys and values of arbitrary types:
<syntaxhighlight lang="ruby">
{1 => 'two', three: 4}
</syntaxhighlight>
An empty Hash:
<syntaxhighlight lang="ruby">
{}
</syntaxhighlight>
===Customizing the default value===
▲<syntaxhighlight lang="ruby">hash = {}
▲hash[666] = 'devil'
hash[777] # => nil
hash[666] # => 'devil'</syntaxhighlight>
A
<syntaxhighlight lang="ruby">hash = Hash.new('unknown key')
hash[666] = 'devil'
hash[777] # => 'unknown key'
hash[666] # => 'devil'</syntaxhighlight>
A
<syntaxhighlight lang="ruby">hash = Hash.new { |h, k| "unknown key #{k}" }
hash[666] = 'devil'
hash[777] # => 'unknown key 777'
hash[666] # => 'devil'</syntaxhighlight>
A
<syntaxhighlight lang="ruby">hash = Hash.new { |h, k| h[k] = "key #{k} was added at #{Time.now}" }
hash[777] # => 'key 777 was added at Sun Apr 03 13:49:57 -0700 2011'
hash[555] # => 'key 555 was added at Sun Apr 03 13:50:01 -0700 2011'
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